8134493: Cleaning inline caches of unloaded nmethods should be done in sweeper
Summary: Clean ICs of unloaded nmethods in sweeper to avoid impact on safepoint duration.
Reviewed-by: kvn, mdoerr
--- a/hotspot/src/share/vm/code/codeCache.cpp Wed Aug 26 12:43:15 2015 +0200
+++ b/hotspot/src/share/vm/code/codeCache.cpp Mon Aug 31 13:49:18 2015 +0200
@@ -745,13 +745,12 @@
void CodeCache::gc_epilogue() {
assert_locked_or_safepoint(CodeCache_lock);
- NMethodIterator iter;
- while(iter.next()) {
- nmethod* nm = iter.method();
- if (!nm->is_zombie()) {
- if (needs_cache_clean()) {
- // Clean ICs of unloaded nmethods as well because they may reference other
- // unloaded nmethods that may be flushed earlier in the sweeper cycle.
+ NOT_DEBUG(if (needs_cache_clean())) {
+ NMethodIterator iter;
+ while(iter.next_alive()) {
+ nmethod* nm = iter.method();
+ assert(!nm->is_unloaded(), "Tautology");
+ DEBUG_ONLY(if (needs_cache_clean())) {
nm->cleanup_inline_caches();
}
DEBUG_ONLY(nm->verify());
--- a/hotspot/src/share/vm/code/compiledIC.cpp Wed Aug 26 12:43:15 2015 +0200
+++ b/hotspot/src/share/vm/code/compiledIC.cpp Mon Aug 31 13:49:18 2015 +0200
@@ -287,6 +287,7 @@
assert( is_c1_method ||
!is_monomorphic ||
is_optimized() ||
+ !caller->is_alive() ||
(cached_metadata() != NULL && cached_metadata()->is_klass()), "sanity check");
#endif // ASSERT
return is_monomorphic;
@@ -321,7 +322,7 @@
}
-void CompiledIC::set_to_clean() {
+void CompiledIC::set_to_clean(bool in_use) {
assert(SafepointSynchronize::is_at_safepoint() || CompiledIC_lock->is_locked() , "MT-unsafe call");
if (TraceInlineCacheClearing || TraceICs) {
tty->print_cr("IC@" INTPTR_FORMAT ": set to clean", p2i(instruction_address()));
@@ -337,7 +338,7 @@
// A zombie transition will always be safe, since the metadata has already been set to NULL, so
// we only need to patch the destination
- bool safe_transition = is_optimized() || SafepointSynchronize::is_at_safepoint();
+ bool safe_transition = !in_use || is_optimized() || SafepointSynchronize::is_at_safepoint();
if (safe_transition) {
// Kill any leftover stub we might have too
--- a/hotspot/src/share/vm/code/compiledIC.hpp Wed Aug 26 12:43:15 2015 +0200
+++ b/hotspot/src/share/vm/code/compiledIC.hpp Mon Aug 31 13:49:18 2015 +0200
@@ -214,7 +214,7 @@
//
// They all takes a TRAP argument, since they can cause a GC if the inline-cache buffer is full.
//
- void set_to_clean();
+ void set_to_clean(bool in_use = true);
void set_to_monomorphic(CompiledICInfo& info);
void clear_ic_stub();
--- a/hotspot/src/share/vm/code/nmethod.cpp Wed Aug 26 12:43:15 2015 +0200
+++ b/hotspot/src/share/vm/code/nmethod.cpp Mon Aug 31 13:49:18 2015 +0200
@@ -1050,7 +1050,7 @@
if( cb != NULL && cb->is_nmethod() ) {
nmethod* nm = (nmethod*)cb;
// Clean inline caches pointing to zombie, non-entrant and unloaded methods
- if (!nm->is_in_use() || (nm->method()->code() != nm)) ic->set_to_clean();
+ if (!nm->is_in_use() || (nm->method()->code() != nm)) ic->set_to_clean(is_alive());
}
break;
}
@@ -1150,7 +1150,7 @@
// Tell if a non-entrant method can be converted to a zombie (i.e.,
// there are no activations on the stack, not in use by the VM,
// and not in use by the ServiceThread)
-bool nmethod::can_not_entrant_be_converted() {
+bool nmethod::can_convert_to_zombie() {
assert(is_not_entrant(), "must be a non-entrant method");
// Since the nmethod sweeper only does partial sweep the sweeper's traversal
--- a/hotspot/src/share/vm/code/nmethod.hpp Wed Aug 26 12:43:15 2015 +0200
+++ b/hotspot/src/share/vm/code/nmethod.hpp Mon Aug 31 13:49:18 2015 +0200
@@ -577,7 +577,7 @@
// See comment at definition of _last_seen_on_stack
void mark_as_seen_on_stack();
- bool can_not_entrant_be_converted();
+ bool can_convert_to_zombie();
// Evolution support. We make old (discarded) compiled methods point to new Method*s.
void set_method(Method* method) { _method = method; }
--- a/hotspot/src/share/vm/runtime/sweeper.cpp Wed Aug 26 12:43:15 2015 +0200
+++ b/hotspot/src/share/vm/runtime/sweeper.cpp Mon Aug 31 13:49:18 2015 +0200
@@ -611,7 +611,7 @@
} else if (nm->is_not_entrant()) {
// If there are no current activations of this method on the
// stack we can safely convert it to a zombie method
- if (nm->can_not_entrant_be_converted()) {
+ if (nm->can_convert_to_zombie()) {
// Clear ICStubs to prevent back patching stubs of zombie or unloaded
// nmethods during the next safepoint (see ICStub::finalize).
{
@@ -645,6 +645,12 @@
assert(result == None, "sanity");
result = Flushed;
} else {
+ {
+ // Clean ICs of unloaded nmethods as well because they may reference other
+ // unloaded nmethods that may be flushed earlier in the sweeper cycle.
+ MutexLocker cl(CompiledIC_lock);
+ nm->cleanup_inline_caches();
+ }
// Code cache state change is tracked in make_zombie()
nm->make_zombie();
SWEEP(nm);